The Class 2 Hazard Warning Diamonds labels are divided into three divisions, each with its own unique hazard class label.

Class 2.1 Flammable Gas Labels - Flammable gases in Division 2.1, such as hydrogen, acetylene, and propane, require a red label with a flame icon on the top and the number 2 or 2.1 at the bottom.

Class 2.2 Non-Flammable Gas Green Labels - Non-flammable gases in Division 2.2, such as nitrogen, refrigerants, and other inert gases, require a green label with a cylinder icon on the top and the number 2 or 2.3 at the bottom.